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The lack of security in communication technologies used in the aviation industry makes it possible to remotely exploit vulnerabilities in critical on-board systems and attack aircraft in flight, according to research presented Wednesday at the Hack in the Box security conference in Amsterdam.

The presentation, by Hugo Teso, a security consultant at consultancy firm N.runs in Germany, who has also had a commercial pilot license for the past 12 years, was the result of the researcher’s three-yearlong research into the security of avionics.

Teso showed how the absence of security features in ADS-B (automatic dependent surveillance-broadcast), a technology used for aircraft tracking, and ACARS (Aircraft Communications Addressing and Reporting System), a datalink system used to transmit messages between aircraft and ground stations via radio or satellite, can be abused to exploit vulnerabilities in flight management systems.

He did not experiment on real airplanes, which would be both dangerous and illegal, according to his own account. Instead Teso acquired aircraft hardware and software from different places, including from vendors offering simulation tools that use actual aircraft code and from eBay, where he found a flight management system (FMS) manufactured by Honeywell and a Teledyne ACARS aircraft management unit.

Using these tools, he set up a lab where he simulated virtual airplanes and a station for sending specifically crafted ACARS messages to them in order to exploit vulnerabilities identified in their flight management systems—specialized computers that automate in-flight tasks related to navigation, flight planning, trajectory prediction, guidance and more.

The FMS is directly connected to other critical systems like navigation receivers, flight controls, engine and fuel systems, aircraft displays, surveillance systems and others, so by compromising it, an attacker could theoretically start attacking additional systems. However, this aspect was beyond the scope of this particular research, Teso said.

Identifying potential targets and gathering basic information about them via ADS-B is fairly easy because there are many places online that collect and share ADS-B data, such as flightradar24.com, which also has mobile apps for flight tracking, Teso said.

ACARS can be used to gather even more information about each potential target, and by combining this information with other open-source data, it is possible to determine with a fairly high degree of certainty what model of FMS a specific aircraft is using, Teso said.

After this is done, an attacker could send specifically crafted ACARS messages to the targeted aircraft to exploit vulnerabilities identified in the code of its FMS. In order to do this, the attacker could build his own software-defined radio system, which would have a range limit depending on the antenna being used, or he could hack into the systems of one of the two main ground service providers and use them to send ACARS messages, a task that would probably be more difficult, Teso said.

Either way, sending rogue ACARS messages to real aircraft would most likely lead to the authorities searching and eventually locating you, the researcher said.

Teso created a post-exploitation agent dubbed SIMON that can run on a compromised FMS and can be used to make flight plan changes or execute various commands remotely. SIMON was specifically designed for the x86 architecture so that it can only be used in the test lab against virtual airplanes and not against flight management systems on real aircraft that use different architectures.
The researcher also created an Android app called PlaneSploit that can automate an entire attack, from discovering targets using Flightradar24 to exploiting vulnerabilities in their FMS, installing SIMON and then performing various actions, like modifying the flight plan.

As previously mentioned, the research and demonstrations were performed against virtual planes in a lab setup. However, the FMS vulnerabilities identified and the lack of security in communication technologies like ADS-B and ACARS are real, Teso said

In a real-world attack scenario, the pilot could realize that something is wrong, disengage the auto-pilot and fly the plane like in the old days using analog systems, Teso said. However, flying without auto-pilot is becoming increasingly difficult on modern aircraft, he said.

Teso did not reveal any specifics about the vulnerabilities he identified in flight management systems because they haven’t been fixed yet. The lack of security features like authentication in ADS-B and ACARS is also something that will probably take a lot of time to address, but the researcher hopes that it will be done while these technologies are still being deployed. In the U.S., the majority of aircraft are expected to use ADS-B by 2020.

N.runs has been in contact with the European Aviation Safety Agency (EASA) for the past few weeks about the issues identified during this research, Teso said, adding that he has been pleasantly surprised by their response so far. “They haven’t denied the issues, they listened to us and they offered resources,” he said. “They’re trying to help us to take this research on a real plane.”

I found out only now, in the following article (Forbes Magazine, April 10th) there are also statements by the FAA, and Flight Management Systems manufacterer Rockwell Collins and Honeywell. Not surprisingly they disagree. Yet, if they wouldn´t, it would be a huge PR damage of course for them...

Here’s an uncomfortable image to keep in mind during your next flight: A rogue hacker who can redirect planes at will with the touch of an Android phone’s screen.

That’s the frightening scenario laid out by Hugo Teso, a security researcher for the German IT consultancy N.Runs, in a presentation at the Hack In The Box security conference in Amsterdam Wednesday. By hijacking a protocol used to send data to commercial aircraft and exploiting bugs in flight management software built by companies including Honeywell, Thales and Rockwell Collins, Teso told the crowd that he could send radio signals to planes that would cause them to execute arbitrary commands such as changes in direction, altitude, speed, and the pilots’ displays.

“You can use this system to modify approximately everything related to the navigation of the plane,” Teso told me in an phone interview following his talk. “That includes a lot of nasty things.”

Update: Several companies and aviation safety organizations now claim that Teso’s research wouldn’t work on actual airplanes. See their comments below.

Hackers and security researchers have warned for years of vulnerabilities in next-generation air traffic control protocols. But Teso focused on a different protocol called Aircraft Communications Addressing and Report System, (ACARS) a simple data exchange system that has evolved over decades to now include everything from weather data to airline schedules to changes to the plane’s flight management system. (FMS)

Teso says that ACARS still has virtually no authentication features to prevent spoofed commands. But he spent three years reverse engineering the flight navigation software that receives ACARS signals to find bugs that allowed him to send his own commands to the systems, either from a software-defined radio that can be tuned to use ACARS or from a compromised airline system. In his talk, Teso demonstrated an Android application he built that allowed him to redirect a virtual plane with just a tap on a map application running on his Samsung Galaxy phone. “ACARS has no security at all. The airplane has no means to know if the messages it receives are valid or not,” he says. “So they accept them and you can use them to upload data to the airplane that triggers these vulnerabilities. And then it’s game over.”

In his presentation, Teso explained that he experimented on used FMS hardware he bought from eBay and FMS training simulation software that was advertised as containing some or all of the same code as the systems in real planes. In our interview he declined to specify exactly what vulnerabilities he discovered in that code, saying that he has instead contacted the Federal Aviation Administration (FAA) and the European Aviation Safety Administration, (EASA) and is working with the affected aerospace companies to fix the problems.

Honeywell, for its part, confirms that it’s been talking to Teso’s employer. But spokesperson Scott Sayres argues that Teso’s work doesn’t necessarily prove any real vulnerabilities in Honeywell’s equipment or software. “We take this seriously and we’re going to work with N.Runs to assess this,” says Sayres. “But as Teso readily admits, the version he used of our flight management system is a publicly available PC simulation, and that doesn’t have the same protections against overwriting or corrupting as our certified flight software.”

Teso’s supervisor at N.Runs, fellow security researcher Roland Ehlies, counters that the vulnerabilities
Teso found in the FMS software weren’t related to the PC version he was testing, but rather to functions that would also exist in real planes. “From our perspective it would work with at minimum a bit of adaptation,” he says.

I’ve reached out to Rockwell Collins, Thales, the EASA and the FAA for comment and will offer an update if I hear back from them.

Update: Spokespeople for the EASA, FAA and Rockwell Collins all echo Honeywell’s statement that while Teso’s attack works on PC simulation software, it wouldn’t give him control of a real plane’s certified flight management system. I’ve included their statements at the bottom of the story.

The increased use of mobile devices in the flight deck, however has introduced new risks. To minimize and eliminate these potential vulnerabilities, we’re prototyping enhanced security features and collaborating with industry regulators, customers and suppliers to develop new standards that will assure the highest levels of protection.”

Both Honeywell’s Sayres and Teso agree that even if a hacker were able to alter the FMS through commands remotely sent over ACARS, the pilots of the plane should be able to override those malicious commands with their own valid ones. Nonetheless, Teso said in his presentation that at the very least, a hacker could perform disruptive stunts like causing the cockpits’ lights to blink wildly or the passengers’ pressurized air masks to drop.

Teso’s presentation is far from the first to raise the potential for hackers to disrupt air travel. Two talks at the Black Hat and Defcon security conferences last summer suggested that hackers could spoof or intercept signals sent using the next-generation air traffic control system Automated Dependent Surveillance-Broadcast or ADS-B. That trick might allow an attacker to suddenly generate the appearance of a non-existent plane in a pilot’s direct path, potentially causing chaos in the air.
Tricks with ACARS to disrupt or hijack planes’ flight management systems–if they bear out in real world tests beyond those Teso has performed–could be far more dangerous. Teso believes that the bugs he’s discovered in those navigation systems can be fixed. In the meantime, those in the cockpit would be wise to keep an eye on their autopilot.

Update: As noted above, aviation safety groups and the FMS software makers have taken issue with Teso’s claims. Their statements are copied below.

The EASA: “For more than 30 years now, the development of certifiable embedded software has been following strict guidance and best practices that include in particular robustness that is not present on ground-based simulation software.”

Rockwell Collins: “”Today’s certified avionics systems are designed and built with high levels of redundancy and security. The research by Hugo Teso involves testing with virtual aircraft in a lab environment, which is not analogous to certified aircraft and systems operating in regulated airspace.

The FAA: “The FAA is aware that a German information technology consultant has alleged he has detected a security issue with the Honeywell NZ-2000 Flight Management System (FMS) using only a desktop computer. The FAA has determined that the hacking technique described during a recent computer security conference does not pose a flight safety concern because it does not work on certified flight hardware. The described technique cannot engage or control the aircraft’s autopilot system using the FMS or prevent a pilot from overriding the autopilot. Therefore, a hacker cannot obtain “full control of an aircraft” as the technology consultant has claimed.”